The unit was formed in the summer of 2005 by Oberleutnant Wilhelm. At first the unit was a regular Heer unit, but changed to the famous Grossdeutschland Division because they wanted an elite German Heer unit in World War II.
As a fighting unit Grossdeutschland was formed in 1939. The core of this four battalion infantry regiment came from the "Wachtregiment Berlin", a guard unit used for ceremonial purposes. The rest of the regiment came from volunteers from all areas of Germany. Thus the name Grossdeutschland was used meaning "Greater Germany". The unit's first designation was "Infanterie-Regiment Grossdeutschland".
At the outbreak of war with Poland the regiment was still in the midst of reorganization. Infanterie-Regiment Grossdeutschland was to stay home and continue the reorganization during the Polish campaign. On 6 September 1939 it was heard that the unit was to be air-landed into Poland. This operation was cancelled due to the advance of Soviet troops into eastern Poland which made the operation unnecessary. In August 1940 the black cuff title Grossdeutschland was issued to the unit and they were now a motorized formation. Although Infanterie-Regiment Grossdeutschland was ready, they did not participate in the immediate invasion of France. However the unit did see some action during the campaign while fighting under the leadership of Heinz Guderian's 19th Armeekorp. Later they were attached to Kleist's command.
From: http://www.grossdeutschland.com/history.htm
Grossdeutschland took part in the invasion of Yugoslavia in April 1941 and then by 22 June, 1941 they headed into Russia during operation Barbarossa. In this campaign they were part of the 2nd Panzerarmee. Distinguishing itself in combat, Grossdeutschland was one of the few German units to reach the outskirts of Moscow. Following the harsh winter battles from Tula to Orel, Grossdeutschland served as an excellent fighting unit while suffering heavy casualties. As a result the unit under went several reorganizations. By April 1942 Armored units were added for better support. The unit was then reformed as "Infanterie-Division (mot) Grossdeutschland". As a much larger unit, Grossdeutschland fought several major engagements ending the year west of Moscow.
On 23 June, 1943 Grossdeutschland was designated "Panzer Grenadier Division Grossdeutschland". By this time Grossdeutschland was truly a reinforced Panzer armee with reconnaissance consisting of Pioneer (engineer) Battalions that were fully armored. During 1943 Grossdeutschland fought at Kharkov, Belgogrod and Kursk during operation Citadel. Later the unit fought in operations north of Karachev in the Orel area. In September 1943, Russian attacks forced Grossdeutschland and other units south across the Dneiper river. These bitterly fought battles sent Grossdeutschland to France for refitting.
In 1944 Grossdeutschland fought
at Targul Frumos, Poland, Lithuania, and Memel just to name a few
places. In November 1944 Grossdeutschland was reformed as "Panzer
Korps Grossdeutschland". Fighting in retreating battles Grossdeutschland
gained the nickname "Die Feuerwehr" (fire brigade). Suffering heavy
casualties Grossdeutschland fought until May 1945. Grossdeutschland
repeatedly faced an enemy with far superior forces while inflicting
powerful blows to them. Grossdeutschland held their own against
enemy superiority in the field.